Endodontics

Question 1

what is clinical assessment of a RCT tooth?

Answer 1

Coronal seal - restorations/crowns. Leakage? Caries?

Amount of remaining tooth structure- ferrule

Is the tooth restorable? Can you isolate it with rubber dam?

Swelling

Sinus

TTP

Buccal sulcus - tender to palpation?

Mobility

Increased pocketing – periodontal disease and root fractures

Question 2

what is radiographic assessment of a RCT tooth?

Answer 2

Root filling - length, quality of obturation e.g. voids

Unfilled/missed root canals

Shape of canal

Patency - fracture instruments, posts, sclerosis

Bone support – mild, moderate, severe

Crown to root ratio (1:1.5)

Pathology - periapical radiolucency – healing?, resorption, perforations

Question 3

what must be done with inadequate root fillings?

Answer 3

be re-treated before restoration

Question 4

what are problems after RCT/re-RCT?

Answer 4

Amount of remaining tooth structure - externally and internally

Restoration type

Lack or no ferrule

Wide post holes e.g. re-RCT

Endodontic complications - fractured instruments, perforations, short/long root fillings

Question 5

how long can root filled teeth be unrestored?

Answer 5

Root filled teeth unrestored for 3 months or longer should generally be re-root canal treated

Question 6

what is the importance of coronal seal?

Answer 6

Technical quality of the coronal restoration significantly more important for apical periodontal health than the technical quality of the root canal treatment

Question 7

what are anterior restoration options?

Anterior teeth with intact marginal ridges

Answer 7

Composite restoration

(Veneer)

Question 8

what are anterior restoration options?

Anterior teeth with intact marginal ridges + discoloured crown

Answer 8

Bleaching or

Veneer

(Crown)

Question 9

what are anterior restoration options?

Anterior teeth with marginal ridges destroyed (post core crowns)

Answer 9

Core build –up with crown

Post crown

Question 10

what is a post/core?

Answer 10

Gains intraradicular support for a definitive restoration

Core provides retention for crown

Post retains the core

Posts do not strengthen or reinforce teeth

Preparation of the root canal for a post, weakens the tooth

Question 11

what is components of a post and core?

Answer 11

Post - placed in the root canal

Core - is what the prosthesis is cemented to e.g. crown or bridge abutment

Question 12

what are guidelines for post placement?

Answer 12

• tooth type
• root filling length
• post width
• Sufficient alveolar bone support, at least half of post length into the root
• Minimum 1:1 post length/crown length ratio
• ferrule

Question 13

what is tooth type guidelines for post placement?

Answer 13

Incisors and canines - post unnecessary if sufficient coronal dentine is present
Avoid in mandibular incisors due to thin/tapering/ narrow mesiodistal roots
Premolars - small pulp chambers and tapering roots. Thin in mesiodistal cross-section and proximal invaginations. If a post is to be placed then place in the widest root canal. Avoid in curved canals to avoid perforations!

Question 14

in terms of placing posts when must you avoid doing them?

Answer 14

Avoid in curved canals to avoid perforations

Question 15

what is root filling length guidelines for post placement?

Answer 15

4-5mm root filling apically

Question 16

what is post width guidelines for post placement?

Answer 16

No more than 1/3 of root width at narrowest point and 1 mm of remaining circumferential coronal dentine

Question 17

what is ferrule guidelines for post placement?

Answer 17

At least 1.5mm height and width of remaining coronal dentine

Question 18

what is a ferrule? what does it prevent? what may be necessary to achieve this?

Answer 18

Dentine collar. Encirclement of 1- 2 mm of vertical axial tooth structure within walls of a crown

Prevents tooth fracture
If crown margin is not placed onto solid tooth, root fracture significantly increased

Orthodontic extrusion or crown lengthening may be necessary to achieve this

Question 19

what is the ideal post?

Answer 19

• Parallel sided
• Non-threaded (Passive)
• Cement Retained

Question 20

what does parallel sided refer to in terms of ideal post?

Answer 20

Avoids ‘wedging’
More retentive than tapered

Question 21

what does non-threaded(passive) refer to in terms of ideal post?

Answer 21

Smooth surface incorporates less stress to remaining tooth than threaded (Active)

Question 22

what does cement retained refer to in terms of ideal post?

Answer 22

Less retentive than threaded posts but cement acts as buffer between masticatory forces and post/toot

Question 23

what are the classification of posts?

Answer 23

Manufacture – pre-formed/prefabricated or custom made
Material – cast metal, steel, zirconia, carbon/glass fibre
Shape – parallel sided or tapered

Question 24

what are prefabricated posts?

Answer 24

Only 1 visit required
No impressions and laboratory visit required
Chairside core build-up
Post and core are different materials
Immediate preparation of core
Large selection of designs and materials

Question 25

what are custom posts? how many visits required? and how made?

Answer 25

Cast from direct pattern fabricated in patients mouth e.g. Duralay

Indirect pattern can be fabricated in the lab e.g. impression of the post hole and wax-up of post and core in lab (most common method)

Unified post and core e.g. made one piece, the same material

2 visits required – impressions and fit. Temporisation between visits and lab stage required. Risk of contamination of the root canal between visits.

Cast post made in Type IV heat hardened gol

Question 26

what types of post material? and their properties?

Answer 26

Metal - cast gold, stainless steel, brass, titanium
Poor aesthetics, root fracture, corrosion, nickel sensitivity. Radiopaque on radiographs.

Ceramics - alumina, zirconia
High flexural strength and fracture toughness. Favourable aesthetics. Difficult retrievability and root fracture common

Fibre - glass, quartz, carbon
Flexible, similar properties to dentine. Aesthetic, retrievable, bond to dentine with DBA’s. Radiolucent on radiographs.

Question 27

what is a core-build up?

Answer 27

Internal part of tooth is built-up with restorative material to replace the lost tooth tissue

The core is prepared. It provides retention and resistance for definitive restorations

Question 28

what are core materials? and their properties?

Answer 28

Composite – most commonly used core material. Tooth coloured so good aesthetics. Bonds to the tooth structure. Technique sensitive, so moisture control required. Used with fibre posts

Amalgam - tend to avoid as retention is required. Poor aesthetics. Core cannot be prepared straightaway – need 24hrs to set. Avoid pinned amalgams.

Glass ionomer - not really used as it absorbs water and core expands in size

Question 29

what is nayyar core?

Answer 29

Root treatment is removed from the root canals.

Amalgam is packed into the root canals and tooth built-up. This provides retention for the amalgam

Cannot be prepared for 24 hrs until amalgam sets

Question 30

what is core design? degree of taper and length required?

Answer 30

Core – taper and length important

6 degree taper

Length required - to allow 2 mm clearance for MCC

Question 31

how to remove gutta percha and what is essential?

Answer 31

Dental dam (pros and cons)

Soften (heat / solvent)

Gates gliddens to minimum size 3 (straight part of canal only)

Use working length and rubber stopper on gates Glidden

Essential to leave 3 – 5 mm GP in apical third

Question 32

what are problems with posts?

Answer 32

Perforation

Core fracture

Root fracture or crack

Post fracture

Question 33

how to manage post perforation?

Answer 33

Repair – internal or external (periradicular surgery)
Extraction

Question 34

what is used to remove posts?

Answer 34

Ultra-sonics
Masseran Kit
Eggler
Moskito Forceps (screw retained)

Question 35

what are post failure rates?

Answer 35

60% due to Restorative reasons

32% due to Periodontal problems

8% due to Endodontic reasons